Study the Role of Catalysts in Biodiesel Production Processes

Decreasing fossil resources and increasing air pollution have made scientists thought of substituting fossil fuels with renewable and clean fuels. Biodiesel is one of such fuels produced through transesterification reaction between a type of alcohol and oil in presence of an acidic or a basic catalyst. Currently production of biodiesel engages with considerations and problems while it has been producing with high cost. Using heterogeneous catalysts are among the measures can be done to reduce biodiesel production cost. Therefore, to better understand the aspects and problems of utilizing other catalysts in this article, different types of catalysts used in biodiesel production have been addressed. Meanwhile, important factors and variables associated with synthesis and application of heterogeneous catalsysts were presented with detail. This includes the introduction and performance evaluation of homogeneous base catalysts, homogeneous acid catalysts, heterogeneous base catalysts, heterogeneous acid catalysts and enzymes. Homogeneous base catalysts have shown better performance than acid catalysts in terms of reaction rate and biodiesel production. Heterogeneous catalysts have the potential of being recovered and reused and so leading to elimination of neutralization and washing steps and therefore reducing waste water and above all reducing the expenditures. Acid catalysts are insensitive to free fatty acids and water and are able to catalyze both transesterificationa and esterification reactions however, the reaction time is much greater than base catalysts. In spite of unique features of enzymes such as insensitivity to free fatty acids or mild reaction conditions, they have not been used very much due to their high prices.